Thermostatic switch assembly employing a pair of adjustably mounted snap switches



D. R. GRAHL ETAL 1966 THERMOSTATIC SWITCHASSEMBLY EMPLOYING A 3231702 PAIR OF ADJUSTABLY MOUNTED SNAP SWITCHES Filed Aug.- 21, 1961 5 k R 6 mm N4 EEF N F R m W WM 4 Y B MK. aha,

United States Patent THERMOSTATIC SWITCH ASSEMBLY EMPLQY- ING A PAIR OF ADJUSTABLY MOUNTED SNAP SWITCHES Darwin R. Gr'ahl, Lincoln Park, and Walter F. Rutter, Birmingham, Mich, assignors to American Radiator 8: Standard Sanitary Corporation, New York, N.Y., a corporation of Delaware Filed Aug. 21, 1961, Ser. No. 132,791 2 Claims. (Cl. 200-138) This invention relates to thermostatically-operated electrical switches, as for example are utilized in domestic heating systems to control the circulat-or for the heat transfer medium and the high limit temperature in the combustion zone.

One object of the present invention is to provide an improved thermostatically operated switch arrangement wherein one or more, and preferably two, electrical snap switches are adjustably disposed to be operated at preselected temperatures by a single thermostatic operator.

A further object of the invention is to provide a thermostatic switch arrangement wherein conventional selfcontained'trigger switches can be utilized, thereby avoiding the time and expense required to devise and test new type switches. I

A further object of the invention is to provide a thermostatic switch arrangement wherein each of a plurality of switches can be easily adjusted and set to be operated at a different temperature by means of a single thermostatic operator.

An additional object of the invention is to provide a thermostatic switch arrangement, including a housing structure, wherein the switch leads may be connected directly to the switch terminals without the necessity for a separate terminal board or terminal blocks.

An additional object of the invention is to provide a thermostatic switch arrangement wherein a low cost shield structure is utilized to prevent the switch lead wires from becoming entangled with, or otherwise interfering with, the movable parts of the thermostatic operator or switch.

A further object of the invention is to provide a low cost thermostatic switch arrangement which is relatively simple structurally, which utilizes to a great extent stock switches and other stock components, and which withstands rough usage, as for example vibration and shock, commonly encountered in heat system applications.

Another object is to provide a thermostatic switch assembly having a housing structure for mounting a tranformer thereon, the arrangement being such that the entire assembly occupies a relatively small total volume.

A general object of the invention is to provide a thermostatic switch arrangement which has desired features of low cost and long service life.

Other objects of this invention will appear from the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

'In the drawings:

FIGURE 1 is a left end view of the FIG. 2 construction which constitutes one form of the invention;

FIG. 2 is a sectional view taken substantially along broken line 2-2 in FIG. 1;

FIG. 3 is a sectional view taken substantially on line 3--3 in FIG. 1; and

FIG. 4 is a view illustrating the use of a transformermounting cover on the FIG. 2 structure.

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Referring in greater detail to the drawings, there is shown thereinla thermostatic switch arrangement comprising a box-like housing 3 including a substantially flat plate-like base wall 1h shown in FIG. 1 as substantially square in general outline. Extending from wall 10 is a peripheral wall defined by the four housing wall sections 12, 14, 16 and 18, said wall sections cooperating with the base wall to form a compartment or chamber in which are disposed the snap switches 20 and 22. Tapped openings may be provided at 19 to accommodate mounting screws for a conventional flat cover plate (not shown) or plate 126 shown in FIG. 4.

Each snap switch may be of conventional construction, and the details thereof are not shown in the drawing, it being only necessary to state that each switch comprises a casing which is provided with terminals 24 and 26 and a depressible plunger or trigger 28. It will be understood that depression of the respective trigger 28 is effective to open or close the circuit across the terminals 24 and 26, depending on Whether the particular switch is a normally closed or normally open structure. As shown in FIG. 1, the switches are arranged in a generally V-shaped pattern. One object of the present invention is to provide an improved means for adjustably mounting the trigger switches, and accordingly in the illustrated embodiment each of the switches is mounted on a generally fiat plate-like lever or support structure 30 or 32, said levers having overlapping end portions to permit their independent pivotal adjustment around the axis of the thermostatic stem 34.

Referring to FIG. 3, thermostatic stem 34 is disposed within a tubular extension 36 preferably formed integrally with base wall 10 and having its terminal end portion suitably surfaced to be fixedly connected with one terminal end portion 38 of a thermostatic bi-metal operator 4%). The bi-mctal is of generally spiral construction and is formed to include a number of spiral coil convolutions, as for example five in number, with the extreme end portion of the bi-metal being suitably connected to the free end of stem 34, as for example in the manner shown in US Patent 2,344,767. It will be understood that by thus disposing thecoil 40 between the fixed tubular extension 35 and stem 34 temperature change in the atmosphere sur rounding the coil is effective to wind and unwind the coil so as to rotate stem 34 in accordance with the magnitude of the temperature change. In order to mount the mechanism in a suitable location, as for example in a support aperture of a furnace bonnet or duct wall, there may be employed a tubular fitting 42 having a threaded section 44 for connection with the supporting or locking structure and having a set screw 46 for locking retention on the tubular extension 36.

As will be seen from FIG. 3, stem 34 includes a reduced diameter section extending through a sleeve 48, preferably in a press fit relation so that the sleeve and stem operate as a unit in the installed device. The upper portion of the sleeve extends through a sheet metal lever or arm 56), with the extreme upper end of the sleeve being staked over onto the upper face of the lever to secure the parts together, and with tab-like portions 52 and 54 extending right angularly from the general plane of lever to constitute striker portions for engagement with the triggers 28 of the respective switches 20 and 22.

As previously noted, switch 20 is carried on a flat plate-like lever 30. In order to economize on materials and provide suflicient clearance for proper operation, the lever 39 is constructed to have an arcuate outer edge 56,

i :3 a straight generally radial edge 58, a generally intermediate circumferentially extending edge 60, a second generally radially extending edge 62, and two other gener ally radially extending edges 64 and as. The lever is formed with two upwardly embossed areas 68 and 743 which form support surfaces for engagement with the undersurface of the casing for trigger switch 2h, suitable rivets 72 and 74' being extended through the embossed portions and bores in the switch casing to fixedly and firmly mount the trigger switch on lever 36. 1

By reference to FIG. 3 it will be seen that lever 3t} has a portion thereof encircling the upstanding post portion of a bushing 76, said bushing having a press fit mounting in the tubular wall structure 36 so that the internal surface of the bushing forms a bearing for the pin-sleeve assembly 34, 48 and so that the upper external surface portion of the bushing (i.e., the post portion) constitutes a bearing for the rotary levers 30 and 32.

Lever 32 is formed as a flat-like element having two generally radial edges 80 and 82, a generally circumferential edge 84, and various interconnecting edges (not numbered). The upper face of lever 32 underlies the trigger switch 22, and rivets 86 and 88 are extended through the lever and suitable openings in the switch casing to mount theswitch casing rigidly and firmly on the lever. The inner end area of the lever 32 encircles the upper por tion of the post structure on bushing 76 so that the post structure serves as a fulcrum for pivotal adjustment of the lever. Locking of the lever in desired positions of adjustment may be accomplished by means of a locking screw 90 which is arranged tobe threaded into a tapped opening in base wall 10, with its shank portion extending through a circumferential slot 92 in the lever and with its head portion overlying the lever face area.

As shown in FIG. 1, terminals 24 and 26 of switches 20 and 22 are freely exposed to receive the snap-on connectors of the conventional insulated wire leads 94 and 96, only two of which are shown in the drawings. Leadin wires may be extended into the switch compartment through suitable knock-out openings as in any of the enclosing walls, as for example throughtan opening in Wall 18. In order to prevent the lead-in wiring from becoming entangled with the switch-mounting levers, the actuator arm 50, or the switch triggers 28, there is preferably provided a shield or barrier means 100, said barrier means including a Hat wall portion 192. and a series of angularly turned legs 104, the terminal ends of which are of reduced width so as to extend through slots in wall 10. After legs 1M are in place the terminal ends thereof may be bent as shown at 1% to lock the shield 1W in place in theicompartment.

The positions of legs 104 are chosen so that the legs ,do not interfere with adjusting movements of levers 30 and 32 or operating movement of the actuator 50. Also, the size and configuration of shield 100 is such that terminals 24 and 26 are left free and exposed to thus permit easy snap-on of the connectors for lead Wires 94 and 96.

Referring now to lever 30, it will be seen that this lever extends through a slot 108 in wall 16 so that a part of the lever is located outside the casing structure for adjustment access. The casing structure is preferably formed as a die casing and is provided with an integral plate-like extension 110 which is in planar alignment with base .Wall 10. One face of extension 110 receives a dial means, preferably taking the form of an elongated plate 112, suitable indicia being provided thereon for cooperation \i/i'th the pointer 114 extending from lever 30. Dial plate 112 is preferably adjustably disposed on extension 110,

I and to facilitate adjusting operations extension 110 is provided with two straight slots 116 arranged to accommodate the shank portions of rivets 118. The arrangement is such as to permit factory calibration of the device by the steps of adjusting dial plate 112 and lever 34) as hereinafter explained.

Assuming that the device is to be used to control the high limit temperature of a heat producer and the cut-in temperature of a heating medium circular (e.g., a fan or water pump) the device may be calibrated by first adjusting lever 32 until the actuator arm 50 operates the trigger for switch 22' at the desired highlimit temperature, as for example 240 F. Set screw may then be operated to lock the switch 22 in place, after which the thermostatic device may be exposed to a lower temperature, as for example 70 F., and the lever 30 adjusted until the trigger for switch 20 is actuated. Whenthe desired position of lever 35) is attained the dial plate '112 may be shifted until the lower test degree mark thereon registers with the pointer 114, after which rivets 118 may be clinched to aflix the plate 112 to the wall extension 110, thereby calibrating the device so that the two switches 20 and 22 are adapted to be actuated at desired temperae tures. The rivets constitute means for clamping thedial plate in its selected adjusted position.

During service the operating range of switch 20 may be adjusted by adjusting the position of lever 30, and for this purpose the lever is provided with a manually engageable handle portion 12d and an arcuate slot 126 through which extends a locking screw 122. It Will be noted that with the illustrated arrangement a single dial means 112 serves to calibrate both switches 29 and 22', thereby economizing to a certain extent on'constr'uction costs. Further economization is attained because of the use of conventional trigger-equipped snap switches for the switch structures 20 and 22 and because of the relatively simple manner of actuating the switches-through an actuator arm 50 having adirect operative connection with both triggers 28 without need for intervening cams, linkages, or the like.

The illustrated control is advantageous inthat the box or casing 8 can with suitable size formation be closed either by a standard outlet box cover, as for example on oil fired heating equipment, or by a transformer-mounting plate, as for example on gaseous fuel type heating equipment. Thus, as shown in FIG. 4, the housing may be closed by a plate 126 having a suitable opening to receive part of the encased coil portion of a transformer 128, appropriate bolts or rivets (not shown) being extended throughthe plate and transformer frame .for mounting purposes. Part of the transformer is exposed so that cooling problems are minimized, while part of the transformer is housed by box 8 so as to provide for compactness. Compactness is further facilitated by the fact that the transformer is mounted generally in front of the switches in substantially axial alignment with the center line of box 8 such that the lateral dimension of the assembly is not increased by the presence of the transformer. This makes for interchangeable use on different types of heating equipment where installation wall area may be limited.

It will be understood that some variation in construction and arrangement may be practiced without departing from the spirit of the invention as defined in the appended claims.

We claim:

1. In combination, a housing structure, including a fiat base wall and a peripheral wall extending generally right angularly therefrom to define a compartment; a thermostatic actuator including a rotary stem extending into the compartment through the base wall, and a switch actuator arm extending from the stem generally parallel with the base wall for arcuate movement around the stem axis; a generally flat plate-like lever adjustably fulcrumed about the stem axis; a snap switch carried on the lever and having an actuating trigger registering with the aforementioned actuator arm; a slot formed in a portion of the aforementioned peripheral wall and accommodating a part of the lever to thus permit the lever to be freely adjusted from outside the compartment; a plate-like extension extending from the housing structure; a dial means carried fiat-wise on the plate-like extension; means mounting said dial means for slidable adjusting movements along said extension; means clamping the dial means in a selected adjusted position on the extension; and an indicator portion connected with the external portion of the lever arm and cooperable with the dial means to denote the temperature actuation range of the snap switch means.

2. In combination, a housing structure having a flat base wall and cooperating side walls defining a compartment; a thermostatic actuator including a rotary stem extending into the compartment through the base wall, and a switch actuator arm extending from the stem generally parallel with the base wall for arcuate movement around the stem axis; first and second plate-like levers extending within the housing structure parallel to said base wall for arcuate adjusting movements around the stem axis; a snap switch carried on the face of each lever remote from the base Wall, each snap switch comprising a casing having a depressible trigger and a plurality of outwardly projecting freely accessible terminals for direct connection with lead wires extending into the housing structure; said snap switches being arranged with the snap switch triggers facing one another at opposite sides of the actuator arm; and a shield structure comprising a first wall portion extending within the compartment generally parallel with the base wall and overlying the actuator arm and the switch triggers, and a second wall portion extending from said first wall portion toward the base wall in the space between the two snap switches so as to shield the actuator arm from entanglement with lead Wires connected to the switch terminals; said terminals being located outside the space circumscribed by the'shield structure, whereby lead wiring can be installed on and re moved from the terminals without disturbing the shield structure.

References Cited by the Examiner UNITED STATES PATENTS 1,976,954 10/ 1934 Mantz 200-138 2,075,951 4/1937 McCabe 200-139 2,213,621 9/1940 Carlson 200-138 2,269,863 1/ 1942 Shaw 200-139 2,464,944 3 194-9 Rosche 200-13 8 2,516,525 7/1950 Muth 200-138 2,521,717 9/1950 Harris 200-138 2,529,652 11/1950 Dicke 200-138 2,585,278 2/ 1952 Shivers 200-139 2,634,312 4/1953 Batcheller 339-258 2,669,618 2/ 1954 Bradley.

2,739,208 3/1956 Ullrich 339-256 2,785,256 3/1957 Nina 200-153 2,901,578 8/1959 Noakes 200-139 2,974,302 3/1961 Ellis 339-258 BERNARD A. GILHEANY, Primary Examiner.

MAX L. LEVY, Examiner. 

1. IN COMBINATION, A HOUSING STRUCTURE, INCLUDING A FLAT BASE WALL AND A PERIPHERAL WALL EXTENDING GENERALLY RIGHT ANGULARLY THEREFROM TO DEFINE A COMPARTMENT; A THERMOSTATIC ACTUATOR INCLUDING A ROTARY STEM EXTENDING INTO THE COMPARTMENT THROUGH THE BASE WALL, AND A SWITCH ACTUATOR ARM EXTENDING FROM THE STEM GENERALLY PARALLEL WITH THE BASE WALL FOR ARCUATE MOVEMENT AROUND THE STEM AXIS; A GENERALLY FLAT PLATE-LIKE LEVER ADJUSTABLY FULCRUMED ABOUT THE STEM AXIS; A SNAP SWITCH CARRIED ON THE LEVER AND HAVING AN ACTUATING TRIGGER REGISTERING WITH THE AFOREMENTIONED ACTUATING ARM; A SLOT FORMED IN A PORTION OF THE AFOREMENTIONED PERIPHERAL WALL AND ACCOMMODATING A PART OF THE LEVER TO THUS PERMIT THE LEVER TO BE FREELY ADJUSTED FROM OUTSIDE THE COMPARTMENT; A PLATE-LIKE EXTENSION EXTENDING FROM THE HOUSING STRUCTURE; A DIAL MEANS CARRIED FLAT-WISE ON THE PLATE-LIKE EXTENSION; MEANS MOUNTING SAID DIAL MEANS FOR SLIDABLE ADJUSTING MOVEMENTS ALONG SAID EXTENSION; MEANS CLAMPING THE DIAL MEANS IN A SELECTED ADJUSTED POSITION ON THE EXTENSION; AND AN INDICATOR PORTION CONNECTED WITH THE EXTERNAL PORTION OF THE LEVER ARM AND COOPERABLE WITH THE DIAL MEANS TO DENOTE THE TEMPERATURE ACTUATION RANGE OF THE SNAP SWITCH MEANS. 